Effect of extractives on conferred and natural durability of Cupressus lusitanica heartwood | Effet des extractibles sur la durabilité naturelle du duramen de cyprès
2010
Mohareb, Ahmed | Sirmah, Peter | Desharnais, Lyne | Dumarçay, Stéphane | Pétrissans, Mathieu | Gérardin, Philippe
• Identification of extractives present in Cupressus lusitanica heartwood has been conducted using GC-MS analyses. The chromatogram of toluene/ethanol extracts indicated the presence of large amounts of benzaldehyde and numerous terpenic compounds such as cedrol, agathadiol, epimanool, bornyl acetate, α-cedrene and β-cedrene. • The effect of these extractives on the natural durability of cypress wood was investigated on heart wood blocks exposed to pure culture of Poria placenta before or after solvent extraction. Weight losses revealed severe fungal degradations on the extracted blocks compared to unextracted ones. • Efficiency of heartwood extractives as inhibitors of the growth of Poria placenta on malt/agar test confirms their contribution to cypress natural durability. • Cypress blocks were treated at 240 °C for different times to reach different levels of thermodegradation to evaluate effect of heat treatment on fungal durability. Results indicate that evaporation of volatile extractives during the first few minutes of heat treatment contribute to decreased wood durability, while longer treatment times lead to the expected improvement of durability. • This study suggests that the content of extractives, which may be modified during wood drying or weathering processes, could be the origin of the conflicting data described in the literature concerning cypress natural durability.
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